Dentin Discs Research Articles

Evaluation of bacterial biofilm, smear layer, and debris removal efficacy of a hydro-dynamic cavitation system with physiological saline using a new ex vivo model: a CLSM and SEM study

IntroductionTo evaluate the bacterial biofilm, smear layer and debris removal efficacy of a hydro-dynamic cavitation system with physiological saline using a new ex vivo model.MethodsSeventy-five dentin discs were prepared from fifty-four extracted teeth. Seventy-five artificial root sockets were prepared. Sixty dentin discs were used to grow 3-week-old bacterial biofilms, while smear layer and debris were produced on fifteen dentin discs. These dentin discs were adhered to the middle third of the artificial root canals. The sixty ex vivo models with biofilm-covered dentin discs were divided into six groups: control, needle with physiological saline, ultrasonic with physiological saline, Odne™ Clean with physiological saline, needle with 3% NaOCl, and ultrasonic with 3% NaOCl. Biofilm removal efficacy was evaluated using confocal laser scanning microscopy. The fifteen ex vivo models with smear layer and debris-covered dentin discs were divided into three groups: control, Odne™ Clean with physiological saline, and 5% NaOCl followed by 17% EDTA. Smear layer and debris removal efficacy was evaluated using scanning electron microscopy. Statistical analysis was performed using one-way analysis of variance for comparisons involving more than two groups. Post-hoc pairwise comparisons were conducted using the Tukey test.ResultsOdneTMClean with physiological saline (98%) performed significantly better than needle irrigation (47%) or ultrasonic activation (54%) with physiological saline (P < 0.05). OdneTMClean with physiological saline removed biofilms as effectively as needle irrigation (97%) or ultrasonic activation (98%) with 3% NaOCl (P > 0.05). Additionally, 5% NaOCl followed by 17% EDTA (score: 1.33) removed the smear layer significantly better than OdneTMClean with physiological saline (score: 4.47) (P < 0.05). However, OdneTMClean with physiological saline (score: 1.27) removed debris as effectively as 5% NaOCl followed by 17% EDTA (score: 1.13) (P > 0.05).ConclusionsOdneTMClean with physiological saline can effectively remove bacterial biofilm and debris from the dentin surface but cannot effectively remove the smear layer. Utilizing OdneTMClean during the final irrigation may enhance root canal cleaning efficacy.

Dentin remineralization induced by experimental composites containing calcium orthophosphate particles.

This study aimed to verify if composites containing dicalcium phosphate dihydrate particles (DCPD) are able to induce dentin remineralization in vitro. Additionally, the mechanical properties of the materials were tested. Four composites with 50 vol% inorganic content and 1 BisGMA: 1 TEGDMA (mols) were prepared, with different DCPD:glass ratios (50:0, 40:10, 30:20 and 0:50). Ca2 + release in water was monitored for 8 weeks using inductively coupled plasma optical emission spectrometry (n = 3). Composites were applied to artificial lesions (180 μm in depth) prepared in dentin discs and the specimens were kept in simulated body fluid for 8 weeks (n = 8-10). Dentin elastic modulus (EM) and hardness (H) across the lesion were determined by nanoindentation (5 mN, 5 s). Mineral density was determined by microCT. Composite degree of conversion (DC) was determined by near-FTIR spectroscopy (n = 3). Fracture strength and elastic modulus were determined using biaxial flexural test (n = 10). Data were analysed by ANOVA/Tukey test, except for mineral density (Kruskal-Wallis, alpha:0.05). Ca2+ release increase linearly with DCPD fraction in the composite (p < 0.001). Lesions kept in contact with composites containing 40 % and 50 % DCPD presented significant increases in EM and H in the outer region (0-90 μm) and in EM in the inner region (90-180 μm) compared to the negative control. MicroCT was not able to differentiate among treatments. DCPD-containing composites presented DC higher than the control (p < 0.01). Flexural strength and modulus were inversely related to DCPD content (p < 0.001). The composite containing 40 vol% DCPD presented the best compromise between mechanical properties and remineralization potential.

Comparative evaluation of antibacterial efficacy of N-acetylcysteine, Aegle marmelos, and chitosan as intracanal medicaments against Enterococcus faecalis biofilm – An in vitro study

Context: The main objective of root canal treatment is the removal of bacteria. Established medicaments and their combinations have been compromised in efficacy against Enterococcus faecalis, causing the need to explore novel intracanal medicaments. Aim: The aim of the study was to evaluate the antibacterial efficacy of chitosan, N-acetylcysteine (NAC), and Aegle marmelos as intracanal medicaments against E. faecalis biofilm. Materials and Methodology: Minimum inhibitory concentration and susceptibility of medicaments determined. Two hundred and forty dentin disc specimens were prepared and inoculated with E. faecalis for 21 days. Samples were divided into four groups (A – N-acetylcysteine; B – Aegle marmelos; C – Chitosan; D –Control) (n = 60), and two subgroups (n = 30) based on the duration of medicament placed (subgroup 1: 24 h, subgroup 2: 7 days). Thereafter, dentinal shavings were retrieved, incubated in agar plate, visible colonies counted, and statistically analyzed. Results: At 24 h Group C1 exhibited the lowest CFUs, followed by Group A1, Group B, and Group D1. On the 7th day, Group B2 showed the lowest CFUs, followed by Group A2, Group C2, and Group D2. Conclusions: Against E. faecalis, NAC has the highest antimicrobial properties closely followed by Aegle marmelos and both provide promising novel possibilities for use as intracanal medicaments.

Effect of propolis added to single-bottle adhesives on water permeation through the hybrid layer.

Water treeing and water droplets are observed within adhesive layers and on the hybridized surface after bonding sound dentin using single-bottle etch-and-rinse adhesives, indicating permeability of the hybrid layer to water. The aim of this study was to assess the efficacy of dentin sealing by adhesives containing propolis by quantifying the area of water transudation from dentinal tubules after dentin hybridization. Brazilian red propolis was added to experimental adhesive and Single Bond (3M/ESPE) adhesive; experimental adhesive and Single Bond without propolis were used as controls. Under simulated pulp pressure, two layers of adhesive were applied to etched human dentin discs. Three minutes after light-curing, the hybridized dentin surface was replicated, and epoxy resin replicas were created to obtain scanning electron microscope images. Data were evaluated using ANOVA and Tukey's test. Single Bond containing propolis significantly decreased water permeation through the hybrid layer compared with the control group. Three minutes after polymerization, the experimental adhesive without propolis had formed a permeable hybrid layer. The addition of Brazilian red propolis significantly reduced surface water on hybridized dentin in a concentration-dependent manner. Two-step etch-and-rinse adhesives containing propolis were effective in reducing water permeation through the hybridized dentin surface.

Effects of Sodium Hypochlorite and Chlorine Dioxide on Human Root Canal Dentine: An ATR-FTIR Spectroscopy Study

Background: It is very important to assess the effects of NaOCl and ClO2 on dentine deproteination because these solutions are in contact with dentine during endodontic treatment and may affect the physical and chemical structure of dentine. Objective: This study aimed to analyze the effects of sodium-hypochlorite (NaOCl) and chlorine-- dioxide (ClO2) on the chemical structure of human dentine by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy. Method: Fifteen human maxillary incisor roots were cut longitudinally into two parallel dentin discs being approximately 4x4x2 mm in size. 30 samples were randomly allocated to 6 groups treated with 5.25% NaOCl or 0.014% ClO2 (1, 5, or 10 minutes); self-control was used. The effect of solutions on the organic and inorganic components of the radicular dentine surface was analyzed using the amide:phosphate ratio and carbonate:phosphate ratio. The intragroup differences (paired t-test) and intergroup differences (one-way analysis of variance and Tukey’s posthoc test) were analyzed. Result: The intragroup comparisons showed the amide:phosphate ratio to be higher at all times at ClO2. NaOCl caused a decrease in the amide:phosphate ratio at 10 minutes (p&lt;0.05). The intergroup comparison showed that NaOCl caused a greater decrease in amide:phosphate at all times compared to ClO2 (p&lt;0.05). All comparisons demonstrated no significant difference in the carbonate: phosphate ratio (p˃0.05). Conclusion: Considering the results of this study, it is recommended to avoid prolonged exposure to minimize NaOCl-induced dentine deproteination. It should also be taken into account that ClO2 increases the amide:phosphate ratio in radicular dentine, and this effect is advantageous in clinical use for collagen structure, contrary to the negative impact of NaOCl.

Comparative evaluation of the degree of conversion of an 8th-generation bonding agent when applied to normal dentin or caries-affected dentin, pre-treated with MMP inhibitors – An in vitro study

IntroductionThe degree of conversion of dentin bonding agents contributes to the success of final restorations in adhesive dentistry. It is clinically relevant, as it is directly related to the overall bond strength that maintains these restorations in place and prevents marginal deterioration. However, Matrix metalloproteinases (MMPs) present within the dentin substrate have been known to have a deleterious effect on the bond stability, due to their collagenolytic activity. Inhibition of the effects of MMPs has been studied, and the use of a pre-treatment protocol that includes MMP inhibiting agents before bonding procedures has been explored, and has been found to increase bond strengths. However, the effect that MMP inhibitors have on dental adhesives has not yet been explored, particularly when being used in caries-affected-dentin (CAD). This study aims to report the degree of conversion of an 8th-generation dentin bonding agent in sound dentin (SD) vs caries-affected dentin after pre-treatment using MMP inhibitors. Materials & methods60 dentin discs were divided into groups of sound and affected dentin, and pretreated with either Cranberry extract or mulberry extract was applied to half of the discs in each group, followed by the application of an eight-generation bonding agent to the pre-treated discs, which were then light cured. The degree of conversion of the adhesive was calculated using ATR-FTIR spectroscopy. ResultsThe degree of conversion was found to be the highest in the samples of sound dentin which were pre-treated with Mulberry extract. ConclusionPre-treatment of the dentin with MMP inhibitors led to an increase in the degree of conversion in sound dentin but not in CAD.

Dentinal Tubule Occlusion and Dentin Permeability Efficacy of Silver Diamine Fluoride Solutions.

This invitro study compared the effect of two commercially available silver diamine fluoride (SDF) products on dentinal tubule (DT) occlusion and dentin permeability. Sixty-six dentin discs (1.0 mm thick) were divided equally into six groups: acid-etched with no treatment (negative control-NC), etched and sealed with nail varnish (positive control-PC), non-etched and treated with Advantage Arrest (AA), non-etched and treated with Topamine (TP), etched and treated with AA, and etched and treated with TP. Eight specimens from each group were tested for permeability using the dye percolation method. The remaining three samples from each group were assessed for dentinal tubule occlusion, depth of SDF penetration, and elemental analysis using a scanning electron microscope coupled with an energy-dispersive X-ray (SEM/EDX) system. One-way ANOVA and Tukey's post hoc test were used to analyze the results. TP exhibited lower (p < 0.05) dye percolation compared to AA. While both SDF materials showed a statistically similar (p > 0.05) penetration depth in the DT, none of them had the ability to completely occlude all the DTs. AA exhibited more silver and fluoride ion deposition on etched dentin than TP, and both materials showed a similar increase in the deposition of Ca and P compared to NC. Whereas the effectiveness of dentin tubule (DT) occlusion varies based on the material used, both tested SDF products exhibit the capability to seal dentinal tubules, decrease dentin permeability, and promote dentin remineralization. These findings suggest their potential advantage in managing dentin hypersensitivity.

In vitro study of the treatment of dentin hypersensitivity with gallic acid combined with sodium fluoride

BackgroundDentin hypersensitivity (DH) is a common oral condition that is associated with severe dental pain. Pain relief is a key focus of the treatment of DH. The purpose of this study was to evaluate the blocking and antacid effects of gallic acid (GA) combined with sodium fluoride (NaF) on dentinal tubules in vitro.MethodsNinety dentin discs from human third molars were treated with 6% citric acid for 2 min. Then, the surface morphologies of ten dentin discs were observed by scanning electron microscopy (SEM). The remaining samples were randomly divided into four groups: the NaF group, which was treated with 1000 ppm NaF; the GA group, which was treated with 4000 ppm GA; the GA + NaF group, which was treated with 1000 ppm NaF + 4000 ppm GA; and the blank group, which was treated with deionized water. The dentin permeability of each sample was measured with a water-filled system before processing and after 7 days of treatment. Dentin morphology and surface deposits were observed by SEM. Then, samples from the NaF, GA + NaF and blank groups were subjected to an acid challenge by incubation with 0.02% citric acid for 2 min. SEM and a water-filled system were used to evaluate the blocking and antacid effects of NaF and GA + NaF.Results1. NaF and GA + NaF significantly decreased dentin permeability. The effect of the GA + NaF treatment was more significant. After acid challenge, both groups still exhibited decreased dentin permeability compared with the initial assessment. 2. Compared with the NaF group, the GA + NaF group had more mineral deposits on the dentin surface and dentin tubules. After acid challenge, the deposits in the GA + NaF group were still clearly visible.ConclusionThe combined effect of GA and NaF on reducing dentin permeability by blocking open dentin tubules is better than that of NaF alone. After acid challenge, the GA + NaF treatment still had a better effect.

Comparison of a Novel Modality of Erbium-Doped Yttrium Aluminum Garnet Laser-Activated Irrigation and Ultrasonic Irrigation against Mature Enterococcus faecalis Biofilm-An In Vitro Study.

In this in vitro study, we aimed to evaluate and compare the antibacterial efficacy of a novel erbium-doped yttrium aluminum garnet laser modality, shock wave enhanced emission of photoacoustic streaming (SWEEPS), ultrasonically activated irrigation (UAI), and single needle irrigation (SNI) against old bacterial biofilm. A two-week-old Enterococcus faecalis biofilm was cultivated on transversal dentinal discs made from the middle third of the roots of single-rooted, single-canal premolars. Biofilm growth was confirmed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The dentine samples were randomly distributed into three experimental groups and one control group based on the irrigation protocol used: Group 1, SWEEPS; Group 2, UAI; and Group 3, SNI. The root canals were irrigated with a 3% sodium hypochlorite solution. Antibacterial efficacy was evaluated quantitatively through bacterial culture and qualitatively through CLSM and SEM. Both SWEEPS and UAI demonstrated a statistically significant reduction in Enterococcus faecalis colony-forming units (CFUs) (p < 0.001), while SNI did not show a statistically significant reduction (p = 0.553). No significant difference was observed between the efficacy of SWEEPS and UAI (p > 0.05). The SWEEPS and UAI techniques were equally effective in eliminating mature E. faecalis biofilm.

Remineralization Effect of Bioactive Glass With and Without Fluoride and Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) on Artificial Dentine Caries: An In Vitro Study.

Background/objectives Dentine hypersensitivity (DH) is a common dental condition marked by transient, sharp pain arising from dentinal exposure. Bioactive materials are capable of remineralization. This study aims to explore the remineralization effect of bioactive glass (BAG) with and without fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), using dentine discs as the test substrate. Materials and methods In this in vitro experimental study, 28 dentine discs were prepared from premolar teeth. Artificial caries were induced by subjecting the dentine discs to demineralization in acid for 72 hours. After demineralization, the discs were treated with various remineralizing dentifrices to evaluate their effects. The dentine discs (n=28) were divided into four groups: group 1 = BioMin (BioMin Technologies, London, United Kingdom), group 2 = NovaMin/Sensodyne Repair (GlaxoSmithKline plc, London, England, United Kingdom), group 3 = Recaldent (CPP-ACP; GC Orthodontics Inc., Alsip, Illinois, United States), and group 4 = deionized water (control group). All discs underwent a 28-day remineralization process using the respective dentifrices assigned to each group. The microhardness of the discs was measured using Vickers microhardness testing at three stages: baseline, post-demineralization, and post-remineralization. Results There was no significant difference in terms of microhardness between groups both at the baseline (F (3, 24) = 1.079, p = 0.995) and after the demineralization process (F (3, 24) = 1.310, p = 0.294). However, a significant difference was identified between the groups after the remineralization process (F (3, 24) = 34.008, p = 0.001). Additionally, the least significant difference (LSD) multiple comparison test was performed. There were significant differences identified in the remineralization condition, with group 1 having the highest values, followed by group 2, group 3, and group 4. Conclusion The results indicate that the remineralization effect on artificially induced dentine caries was more pronounced with bioactive glass containing fluoride compared to bioactive glass without fluoride and CPP-ACP.

Evaluation of the cytotoxicity of new formulations of cariostatic agents containing nano silver fluoride: an in vitro study.

The objective of the study was to assess the indirect cytotoxicity of 600ppm and 1500ppm nano silver fluoride (NSF) compared to other commercial cariostatic agents. 56 dentin discs with 0.4mm in thickness were obtained from intact human molars and adapted to artificial pulp chambers (APCs). The discs were divided into seven groups according to treatment (n = 8): no treatment (positive control-PC), 29% hydrogen peroxide (negative control-NC), 30% Cariestop (CS30), 38% Riva Star (RS38), 38% Advantage Arrest (AA38), 600ppm NSF (NSF600), and 1500ppm NSF (NSF1500). The cariostatic agents were applied on the occlusal surface of the dentin discs (facing upward), and the pulp surface (facing downward) remained in contact with the culture medium. Immediately after the treatments, the extracts (DMEM + cariostatic agent components diffused through the discs) were collected and applied to MDPC-23 cells, which were assessed for viability (CV-alamarBlue, live/dead), adhesion/spreading (F-actin), alkaline phosphatase (ALP) activity, and mineralization nodule (MN) formation. The data were statistically analyzed by ANOVA/Games-Howell (p = 0.05). CV and ALP activity in CS30, RS38, AA38, and NSF600 were similar to PC (p > 0.05). MN formation significantly decreased only in NC, CS30, RS38, and AA38 compared to PC (p < 0.001). Only NSF600 and NSF1500 did not differ from PC (p > 0.05) with mineralization nodules, and this specific cell activity significantly decreased in all other groups (p < 0.05). NSF solutions (600ppm and 1500ppm) did not cause transdentinal toxicity on MDPC-23 cells.

Antimicrobial Silk Fibroin Methacrylated Scaffolds for Regenerative Endodontics

IntroductionRecognizing the necessity of novel disinfection strategies for improved bacterial control to ultimately favor tissue regeneration, this study developed and characterized antibiotics-laden silk fibroin methacrylated (SilkMA) scaffolds for regenerative endodontics. MethodsSilkMA-based solutions (10% w/v) containing Clindamycin (CLI) or Tinidazole (TIN) (0 – control; 5, 10, or 15% w/w) or the combination of both drugs (BiMix CLI/TIN 10%) were electrospun and photocrosslinked. Morphology and composition were assessed using scanning electron microscopy and Fourier-transform infrared spectroscopy. Additionally, swelling and degradation profiles were also determined. Cytotoxicity was evaluated in stem cells from apical papilla. Antibacterial efficacy was tested using direct and indirect contact assays against Aggregatibacter actinomycetemcomitans/Aa, Actinomyces naeslundii/An, Enterococcus faecalis/Ef, and Fusobacterium nucleatum/Fn. E. faecalis biofilm inhibition on dentin discs was specifically evaluated for BiMix-laden scaffolds. Data were statistically analyzed with a significance level of 5%. ResultsScanning electron microscopy revealed that all scaffolds had similar characteristics, including fiber morphology and bead absence. Fourier-transform infrared spectroscopy showed the incorporation of CLI and TIN into the fibers and in BiMix scaffolds. Antibiotic-laden scaffolds exhibited lower swelling capacity than the control and were degraded entirely after 45 days. Scaffolds laden with CLI, TIN, or BiMix throughout all time points did not reduce stem cells from apical papilla's viability. CLI-laden scaffolds inhibited the growth of Aa, An, and Ef, while TIN-laden scaffolds inhibited Fn growth. BiMix-laden scaffolds significantly inhibited Aa, An, Ef, and Fn in direct contact, and their aliquots inhibited An and Fn through indirect contact, with additional biofilm inhibition against Ef. ConclusionsBiMix-laden SilkMA scaffolds are cytocompatible and exhibit antimicrobial effects against endodontic pathogens, indicating their therapeutic potential as a drug delivery system for regenerative endodontics.

Antibiofilm effect of different concentrations of silver nanoparticles combined with calcium hydroxide against Enterococcus faecalis biofilm: An exvivo study.

This study aimed to evaluate the antibiofilm activity of different concentrations of silver nanoparticles (AgNPs) in combination with calcium hydroxide [Ca(OH)2] against Enterococcus faecalis biofilm. On an E. faecalis biofilm on dentin discs, the following medicaments were applied for 7 days (n = 13/group): 0.005% AgNPs+Ca(OH)2, 0.01% AgNPs+Ca(OH)2, 0.02% AgNPs + Ca(OH)2, Ca(OH)2 and saline/control. Specimens were stained with LIVE/DEAD® BacLight™ dye and analysed with confocal laser scanning microscopy. Proportion of dead bacteria was calculated and analysed. There was a significant reduction in E. faecalis biofilm in all medicament groups (43.5%, 49.1%, 69.1%, 48.7%) respectively, compared with control group (2.54%) (p < 0.001). The 0.02% AgNPs + Ca(OH)2 group demonstrated the most significantly superior antibiofilm effect, with no significant difference between remaining groups. In conclusion, combining 0.02% AgNPs enhanced the antibiofilm effect of Ca(OH)2 on E. faecalis biofilm compared with lower AgNPs concentrations.

Microhardness and characterization of human dental tissue after application of enzymatic chemical agents: In vitro study.

The use of enzymatic chemical agents are papain-based materials used in the selective removal of decayed dentin tissue, assisting in conservative techniques and reducing the chances of accidental pulp exposure. A research protocol was subjected to and approved by an Ethics Committee. Using a reporting guide for laboratory studies (CRIS). Healthy human teeth comprised the produced dentin discs subjected to polishing and washing in an ultrasonic bath. Next, the discs received material application according to the experimental groups: water-soluble gel for two minutes, 37% phosphoric acid for 15 seconds in dentin and 30 seconds in enamel, Papacárie Duo (PD) for 30 seconds and two minutes, and Brix 3000 (BX) for two minutes and 30 seconds. The measurement of material pH used solutions at concentrations of 0.1 ml and 2.7 ml prepared for each enzymatic agent. Then, a bench pH meter (n=10) and pH indicator strips determined pH values. The discs underwent the Knoop hardness test (n=10). The sample calculation was performed using the GPower software with α = 0.05, effect 0.63 and power of 95%. Descriptive statistical analysis was carried out for pH, one way ANOVA supplemented by Tukey for knoop hardness and Spearman correlation for pH measurement techniques. The enamel hardness findings indicated that, after material application, ECAs do not statistically differ from water-soluble gel (p<0.05). The dentinal hardness analysis presented a statistical difference in phosphoric acid from the other groups (p<0.05). In the pH test, BX values were lower (4.37 ± 0.01) than PD (4.85 ± 0.06). The groups statistically differed (p<0.05). ECAs for removing decayed dentin tissue did not significantly alter the hardness of enamel and dentin, removal of the smear layer is time-dependent and presents acidity. Key words:Dental caries, Hardness, Dental materials, Papain.

An SEM study on the effect of 9.3-µm CO2 laser on dentinal tubules for hypersensitivity treatment.

In-vitro studies were performed on dentin of extracted human molars to investigate the effectiveness of 9.3μm CO2 laser irradiation to occlude dentinal tubules. The observed occlusion of dentinal tubules with the irradiation was compared with application of three reagents: 2% Sodium Fluoride gel, an aqueous solution of hydroxyapatite nanoparticles and an equal mix of the two. We show that 9.3μm CO2 laser irradiation occludes dentinal tubules, and the use of laser irradiation produces better occlusion of the opened tubules compared to the use of topical reagents. Nine extracted and cleaned human molars were cut to obtain dentin disks of thickness of 3-5mm. Each disc was divided into four quarters, and each quarter served as two samples corresponding to irradiated and non-irradiated group counterparts. Five disks were used to study the effect of various laser irradiation energies on the dentinal tubules to find a good pulse fluence for occlusion of the dentinal tubules, and four disks were used for studying the effects of reagents and irradiation at the pulse fluences found in the first part of the study. The samples were irradiated with a beam diameter of 1mm (1/e2) at 15Hz pulse repetition rate, scanned automatically using a set of scanning mirrors. Samples were imaged using Scanning Electron Microscope (SEM) which were processed to determine tubule diameter. Safety of the irradiation treatment was investigated on 6 samples by measuring pulpal temperature rise. The effect of three topical reagents corresponding to 2% Sodium Fluoride gel (F), Hydroxyapatite nanoparticles (HA) and an equal mix of F and HA (HAF) on dentinal tubule occlusion was evaluated and compared with the laser irradiation. In all examined cases, laser irradiation at a fluence of 0.81J/cm2 resulted in a temperature increase less than 3°C which is safe, and no surface cracking was observed. There is a threshold pulse fluence of 0.27J/cm2 above which, laser produced surface melting. At a pulse fluence of 0.81J/cm2 a layer of recast of melted dentin was formed. Under this layer, peritubular dentin melting and occluding of the dentinal tubules was observed. Application of either F or HA or HAF did not produce visible occlusion effect on open tubules after washing and microbrushing with excess distilled water. 9.3μm CO2 laser irradiation on extracted human molar dentin at pulse fluence of 0.81J./cm2 resulted in tubule area reduction by 97% without rising pulpal temperatures to unsafe levels.

Effect of inositol hexaphosphate acid versus polyacrylic acid on dentin properties and adhesion of a self-adhesive restorative material to dentin

ObjectiveThis study evaluated the effect of 2% inositol hexaphosphate (IP6) and 10% polyacrylic acid (PAA) on dentin surface micromorphology, matrix/mineral ratio, microhardness, and resin−dentin shear bond strength (SBS) of a self-adhesive restorative material (Surefil™ One; Dentsply Sirona, Konstanz, Germany). Materials and methodsHuman permanent molar mid-coronal dentin discs were either not treated (control), conditioned with 10% PAA (Dentin Conditioner, GC, Tokyo, Japan) for 20 s, or etched with 2% IP6 for 20 s. Dentin surface micromorphology (etching pattern), matrix/mineral ratio, and microhardness were characterized by a scanning electron microscope (SEM), a confocal Raman microscope and a microhardness tester using the Vickers indenter, respectively. Sound molars were cut flat, mounted, surface treated and restored with Surefil™ One, Dentsply. The shear bond strength (SBS) was evaluated using a universal testing machine at 24 h and after 10k thermo-cycles. The failure modes were assessed. One-way and two-way analysis of variance (ANOVA) followed by the Tukey's multiple comparisons test was used for the statistical analysis. ResultsIP6 etching resulted in a more aggressive and uniform etching pattern compared with PAA. The mineral/matrix and Vickers microhardness of IP6-etched dentin were significantly less than those of PAA-conditioned dentin. IP6 etching significantly improved the resin−dentin SBS compared with the control group (no treatment) at 24 h and after thermo-cycling. Adhesive failures were the most predominant in all study groups. ConclusionInositol hexaphosphate acid etching deteriorated dentin microhardness and resulted in substantial demineralization, however, it eliminated the dentin smear layer completely and created marked micromorphological alteration at dentin surface, significantly increasing the resin−dentin SBS of a self-adhesive restorative material.

Comparative evaluation of antimicrobial efficacy of chitosan nanoparticles and calcium hydroxide against endodontic biofilm of Enterococcus faecalis: An in vitro study.

The aim of the study was to assess and evaluate the antimicrobial effectiveness of chitosan nanoparticles (CSNPs) with calcium hydroxide in the elimination of Enterococcus faecalis. Using the broth microdilution method, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of calcium hydroxide and CSNPs were measured. The antibiofilm effect of calcium hydroxide and CSNPs against E. faecalis biofilm was qualitatively analyzed using a crystal violet assay. A 7-day-old biofilms of E. faecalis grown on dentine discs were assigned to the following three groups (n = 11 dentine discs), normal saline (group I), calcium hydroxide (group II), and CSNPs (group III). Quantification of live and dead cells using confocal microscopy was done to evaluate the antibiofilm efficacy of the medicaments included in the study. MIC of calcium hydroxide and CSNPs against E. faecalis was observed at 2.5 mg/mL and 0.31 mg/mL, respectively. MBC of calcium hydroxide and CSNPs was observed at 2.5 mg/mL and 0.31 mg/mL, respectively. Using Crystal Violet (CV) assay, calcium hydroxide and CSNPs showed biofilm inhibition at concentrations of 2.5 mg/mL and 0.625 mg/mL, respectively. Confocal laser scanning microscopy analysis found that both calcium hydroxide and CSNPs showed a significant decrease in viable cells at their MBC values compared to the control group's normal saline. CSNPs showed a significantly lower percentage of live cells than calcium hydroxide (P < 0.05). The study results reveal that the antimicrobial efficacy of CSNPs is better than calcium hydroxide and normal saline against E. faecalis biofilm.

Effect of continuous vs sequential chelation on the mechanical properties of root dentin: An ex vivo study

ObjectivesTo evaluate the mechanical properties of root canal dentin treated with sodium hypochlorite (NaOCl) in combination with hydroxyethylidene diphosphonic acid (HEDP) or ethylenediaminetetraacetic acid (EDTA). MethodsFor testing fracture resistance, 45 single-rooted teeth were instrumented and irrigated with NaOCl/HEDP, NaOCl/EDTA, or distilled water. Fifteen untreated teeth served as control. After obturation, specimens from the experimental groups were thermocycled, dynamically-loaded, and then statically-loaded in a universal testing machine until failure. For flexural strength analysis, 15 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Root segments were sectioned into dentin bars and tested for flexural strength using a universal testing machine. For microhardness evaluation, 20 teeth were instrumented and irrigated with NaOCl/HEDP or NaOCl/EDTA. Dentin disks from the coronal-third of each root segment were prepared, one before and one after irrigation, for microhardness testing with a Knoop hardness tester. ResultsThe highest fracture resistance was recorded in the untreated group, and the lowest in the EDTA group. Although the HEDP group had higher fracture resistance than the EDTA group, the distilled water group demonstrated even greater fracture resistance than the HEDP group. Specimens treated with HEDP had significantly higher flexural strength and microhardness values when compared with those treated with EDTA. ConclusionThe fracture resistance, flexural strength, and microhardness of root canal dentin were higher when root canals were irrigated with NaOCl/HEDP, when compared with NaOCl/EDTA. Clinical significanceIrrigating root canals with NaOCl combined with HEDP significantly improves the mechanical integrity of root canal dentin compared to the use of NaOCl with EDTA.

The effect of different conditioning agents on dentin roughness and collagen structure

ObjectivesTo assess the impact of various organic and inorganic acids on the roughness, demineralization, and collagen secondary structures of human dentin and to compare these effects with those of traditional agents, specifically phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA). MethodsCoronal dentin discs (n = 10) were examined by optical profilometry (roughness) and ATR-FTIR before and after conditioning with 32 % PA, 3 % nitric acid (NA), 20 % citric acid (CA), 20 % phytic acid (IP6) or 17 % EDTA. Spectra data were processed to quantify dentin demineralization (DM%) and percentage area of amide I curve-fitted components of β-turns, 310-helix, α-helix, random coils, β-sheets, and collagen maturation index. Statistical analysis was performed by one-way ANOVA or Kruskal-Wallis for DM% and roughness parameters, and paired t-test/Wilcoxon test for amide I components at significance level set at α = 0.05. ResultsAll treatments resulted in increased roughness parameters, with the most significant changes occurring primarily with PA, while EDTA exhibited the least changes. DM% was NA>PA>IP6>CA>EDTA in a descending order. Regarding amide I components, NA demonstrated a significant reduction in β-turns, 310-helices, and α-helices and it increased β-sheets and random coils. PA resulted in reduction in β-turns and α-helices while it increased β-sheets. CA and EDTA did not cause significant changes. The collagen maturation index significantly increased only after IP6 treatment. ConclusionsThe effect on dentin roughness parameters, demineralization, and collagen secondary structures varied based on the type of dentin surface treatment. Clinical significanceUnderstanding the impact of acids on the intrinsic properties of dentin is clinically essential for gaining insights into how these effects influence adhesion to dentin, the long-term stability of resin-based restorations, and the success of remineralization therapies.

Comparison of remineralization ability of tricalcium silicate and of glass ionomer cement on residual dentin: an in vitro study

ObjectiveThis study aimed to compare the remineralization effects of a calcium silicate-based cement (Biodentine) and of a glass ionomer cement (GIC: Fuji IX) on artificially demineralized dentin.MethodsFour standard cavities were prepared in dentin discs prepared from 34 extracted sound human third molars. In each disc, one cavity was covered with an acid-resistant varnish before demineralization (Group 1). The specimens were soaked in a chemical demineralization solution for 96 h to induce artificial carious lesions. Thereafter, one cavity each was filled with Biodentine (Group 2) and GIC (Group 3), respectively, and one carious lesion was left unrestored as a negative control (Group 4). Next, specimens were immersed in simulated body fluid (SBF) for 21 days. After cross-sectioning the specimens, the Ca/P ratio was calculated in each specimen by using scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, data were analyzed using repeated-measures ANOVA with post-hoc Bonferroni correction.ResultsBoth cement types induced dentin remineralization as compared to Group 4. The Ca/P ratio was significantly higher in Group 2 than in Group 3 (p < 0.05).ConclusionThe dentin lesion remineralization capability of Biodentine is higher than that of GIC, suggesting the usefulness of the former as a bioactive dentin replacement material.Clinical relevanceBiodentine has a higher remineralization ability than that of GIC for carious dentin, and its interfacial properties make it a promising bioactive dentin restorative material.